The present invention refers to extracts from the fungus Guignardia sp., and also a new isolate compound from the aforementioned extract, both having antimicrobial activities, particularly antibacterial and antifungal activities, and their use in pharmaceutical compositions.
The new compound, isolated from the extract of the fungus Guignardia sp., presents a dioxolanone ring, having the following formula: 
The search for extracts obtained from plants, protista, fungi or animals and isolated molecules, identified and characterised from these extracts, having antimicrobial activities, has become one of the main motivators for the research and development of new drugs providing a larger scope of action and less toxicity. Furthermore, various pathogens that infect both animals and human beings are becoming resistant to many of the drugs presently in use which heightens the interest for new molecules.
After the major development of synthetic drugs that marked the second half of the 20th century, the nineties stand out as the era of research for drugs based on active principles obtained or isolated from natural products. The use of medicinal plants, protista, fungi and animals as raw material for isolating pure natural products, or for the obtainment of extracts and/or the formulation of phytotherapeutic products, consists an integral part of modern therapeutics.
The publications of natural products listed in Chemical Abstracts between 1985 and 1995 show that 21.1% were made by Japan, 10% by the US, another 10% by China, 8% by Germany, 8% by India, 4% by France and only 1.6% were contributed by Brazil (Gottlieb, O. R. xe2x80x9cNatural products research in Brazil.xe2x80x9d Cixc3xaancia e Cultura. Journal of the Brazilian Association for the Advancement of Science. 49. (5,6). 315-320. 1997).
Through the years, natural products have formed the basis for the treatment of illnesses of all the ancient cultures and continue to be the main source of primary health treatment for 80% of the world population. Sophisticated systems of traditional medicine have existed for thousands of years in many countries, such as China and India. Medicinal plants, protista, fungi and animals are also extensively used in the traditional systems of African medicine. Many phytodrugs are used in Europe and the US. Numerous examples of well known active principles derived from natural products can be cited, such as, for example, from plants: glycosides for the treatment of heart diseases obtained from Digitalis purpurea L.; the antihypertensive and tranquilliser reserpine, derived from the Rauvolfia serpentine (L.); quinine, antimalarial agent, from the Cinchona ssp.; the opiatic analgesics codeine and morphine from the Papaver somniferum L.; the antileucemic agents Vinblastine and Vincristine, from the Catharanthus roseus (L.) (see Baker, J. T., Borris, R. P., Cart{acute over (e )}, B., Cordell, G. A., Soejarto, D. D., Cragg, G. M., Gupta, M. P., Iwu, M. M., Madulid, D. R. and Tyler, V. E. xe2x80x9cNatural product drug discovery and development: New perspectives on international collaborationxe2x80x9d. Journal of Natural Products. 58 (9), 1325-1357. 1995).
South America is becoming the focal point of much research in the field of natural products because it is considered one of the largest centres of biodiversity. South America is the continent of origin of many plants, Protista, fungi and animals that have already furnishedxe2x80x94or demonstrate the potential to furnishxe2x80x94important products used in drugs.
As an example of the attempt to find natural molecules capable of acting against infectious agents, various efforts have been made, for example, to isolate and characterise at molecular level, a broad band of natural peptidic antimicrobial components obtained from animals (amphibians, frogs, mammals, insects), plants, fungi and bacterial species (Hanckoc et al., 1995). These biologically active peptides vary as to the scope of activity, mode of action, molecular weight (from 1.1 to more than 10 kDa), genetic origin and biochemical properties.
Various programs with the objective of identifying metabolites in extracts from fungi are also under way. Ganoderma pfeifferi Bres. (synonimous Ganoderma cupreolaccatum Kalchbr., Ganoderma soniese Steyaert) is a basidiomycete found only in Europe, and which lives on Fagus and various other trees such as Aesculus, Acer, Fraxinus, Prunus and Quercus. This species of basidiomycete is distinguishable from other older species such as Ganoderma lucidum and Ganoderma resinaceum by its dark brown context. Ganoderma pfeifferi is one of the lesser known species of the Ganodermaceteae family from the phytochemical investigation point of view. However, a reasonable number of triterpenes, polysaccharides and steroids, with interesting biological and pharmacological activities, have been isolated from the extracts of G. lucidum and G. applanatum. 
Mothana et al (Mothana, R. A. A., Jansen, R., Jxc3xclich, W. and Lindequist, U. xe2x80x9cGanomycins A and B, new antimicrobial farnesyl hydroquinones from the basidiomycete Ganoderma pfeifferi. J. Nat. Prod., 63. 416-418. 2000) isolated and elucidated the structure of two hydroquinones obtained from the extract of the dichloromethane of G. pfeifferi. These compounds (i) acid 2-[2-(2.5 dihydroxyphenyl)-ethylidene]-11-hydroxy-6.10-dimythyl-undeca-5.9-dienic and (ii) acid acid 2-[2-(2.5 dihydroxyphenyl)-ethylidene]-6.10-dimythyl-undeca-5.9-dienic present antibacterial activity.
Marine fungi have also been cited as potential sources of active secondary metabolites of biological and chemical interest for the development of new pharmaceutical compositions. Afiyatullov et al (Afiyatullov, S. S., Kuznetsova, T. A., Isakov, V. V., Pivkin, M. V., Prokofeva, N. G., Elyakov,G. B. xe2x80x9cNew Diterpenic Atrosides of the fungus Acremonium striatisporum isolated from a Sea Cucumber. J.Nat. Prod. 63.848.-850.2000)] investigated the fungus Acremonium striatisporum isolated from the sea cucumber Eupentacta fraudatrix. The authors isolated and characterised two new diterpenic glycosides from this fungus (named virescinosides M and N) also isolating, furthermore, three known compounds (virescinosides A, B and C). These compounds presented cytotoxic effects on the eggs of the Strongylocentrotus intermedius during initial stages of development (MIC50=2.7-20 xcexcM) and also demonstrated cytotoxic activity, in vitro, against tumorous cells of Ehrlich""s carcinoma (IC50=10-100 xcexcM).
Furthermore, various other examples can be cited concerning the obtainment of extracts resulting from the fermentation of fungi and/or molecules obtained from these when showing interesting biological activity, amongst others, against human cytomegalovirus (Guo, B., Da, J. R., Ng, S., Huang, Y., Leong, C., Ong, W. e Cartxc3xa9, B. xe2x80x9cCytonic Acids A and B: novel tridepside inhibitors of hCMV protease from Endophytic fungus Cytonaema species. J. Nat. Prod. 63.602-604-2000).
The U.S. Pat. No. 3,891,506 describes a substance, named quintomycin, with potential use as an antibiotic which is produced by the fungus Streptomyces lividus. 
Concerning the fungus belonging to the genus Guignardia, it is possible to cite the obtainment of alkaline lipolitic enzymes isolated from this micro-organism, in particular from G. laricina and G. paulowniae, and its uses in detergents (see U.S. Pat. No. 5,919,746).
Despite being quite vast, medical knowledge still remains incomplete as to the fight against pathogenic micro-organisms having already infected the human organism, especially those originating from (i) nosocomial infections where the aerobiological micro-organisms constitute, for example, an important vector, (ii) food poisoning and (iii) the contamination of water. Furthermore, such micro-organisms may also become resistant to any known drug, even the latest generation ones, due to their possible biological mutations.
In this context, the development of new, more efficient drugs for the treatment of infections caused by these micro-organisms becomes urgent, especially bacteria and fungi, with the capability of having effect in cases where many strains have already become resistant to the drugs commonly employed and commercially available. In this sense, the search for natural extracts obtained from animals (amphibians, frogs, mammals, insects), plants, fungi and bacteria species has shown to be an interesting alternative to attend to the demand for more efficient drugs with lower toxicity to treat patients with generalised infections, caused by infection through fungi and bacteria, and which are common, for example, in hospital environments.
One of the purposes of the present invention is to provide extracts obtained from the fermentation of the fungus Guignardia sp.
Another purpose of the present invention is to provide, from the aforementioned extract of the fungus Guignardia sp., a new molecule containing a dioxolanone ring, or a salt of the same, having the following formula: 
A first embodiment of the following invention relates to a pharmaceutical composition including the extract resulting from the fermentation of the fungus Guignardia sp. combined with a pharmaceutically acceptable vehicle.
A second embodiment of the present invention refers to a pharmaceutical composition including the molecule (Z)-5-benzylidene-2-isopropyl-4-oxo-1.3-dioxolane-2-carboxyl acid or a salt of the same combined with a pharmaceutically acceptable vehicle.